JPH1181998A - Secondary air passage switching valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the structure of closing valve while preventing opening thereof due to the pressure fluctuation by arranging a displacing member for opening and closing a valve port in a flow-out passage side, and forming the displacing member with a first pressure receiver part for receiving the pressure in a direction of closing the valve port and a second pressure receiver part for receiving the pressure in a direction of opening the valve port. SOLUTION: A closing valve 100 receiving air supply from an air pump is formed by connecting a lower plate 108 and a diaphragm 109 with rivets 113, and the lower plate 108 is formed with a first pressure receiver part 108b for receiving the pressure in a direction of closing a valve port 103. The diaphragm 109 is formed with a second pressure receiver part 109a for receiving the pressure in a direction of opening the valve port 103. In the case where abnormality is generated in a check valve 112 and the exhaust gas is reversely flowed and the exhaust pressure is applied to each pressure receiver part 108b, 109a, since the projecting area of both the pressure receiver parts 108b, 109a are formed equal to each other, the force for displacing the displacing member 108 generated by the exhaust pressure is offset so as to prevent the opening of the closing valve 100.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary air passage provided in a secondary air passage for guiding air to an exhaust pipe (exhaust manifold) of an internal combustion engine (engine) for opening and closing the secondary air passage. It is about a valve.

[0002]

2. Description of the Related Art A secondary air passage opening / closing valve (hereinafter abbreviated as an opening / closing valve) opens when an air pump is operating to supply secondary air to an exhaust pipe, and when the air pump is stopped. A type of check valve that closes to prevent exhaust gas from flowing back to the air pump.

Since the pressure of exhaust gas (hereinafter, abbreviated as exhaust pressure) constantly fluctuates, the pressure fluctuation (pulsation) may cause the on-off valve to open. In order to prevent the valve opening (backflow of exhaust gas) due to the pressure fluctuation, for example, in the on-off valve described in US Pat. No. 5,491,976, as shown in FIG. Are provided, the directions of the exhaust pressures acting on the two diaphragms 30 and 44 are opposite to each other, the area of the first diaphragm 30 is made larger than the area of the valve element 54, and the coil spring 6
The elastic force in the direction to close the valve is always applied to the valve element 54 by the reference numeral 4.

[0004]

By the way, in the above-mentioned conventional on-off valve, since the exhaust pressure in the opening direction acts on the valve element 54, the force due to the area difference between the first diaphragm 30 and the valve element 54 and the coil spring With the elastic force of 64, a force in the valve closing direction is always applied to the valve body 54. For this reason, in the above-mentioned conventional on-off valve, the force required to open the valve increases, so that the pressure (opening pressure of the air pump) for opening the valve is applied to the second diaphragm 44 and the first pressure chamber is opened. By guiding the discharge pressure of the air pump to 38 and applying a pressure to the first diaphragm 30 to open the valve, the valve element 54 is configured to open quickly.

Therefore, the above-mentioned conventional on-off valve has a complicated structure, which results in an increase in the size of the on-off valve and an increase in the manufacturing cost of the on-off valve. In view of the above, an object of the present invention is to simplify the structure of an on-off valve while preventing valve opening due to pressure fluctuation.

[0006]

The present invention uses the following technical means to achieve the above object. Claim 1,
In the inventions described in 3 and 4, the displacement members (108, 109) having the valve portions (108a) for opening and closing the valve ports (103) are disposed on the outflow passage (105) side. Then, the first pressure receiving portion (108b) that receives the pressure in the direction to close the valve port (103) and the valve port (1) are applied to the displacement members (108, 109).
03) receiving a pressure in a direction to open the second pressure receiving portion (109).
a) and both pressure receiving portions (108b, 109
a) shows displacement members (108, 10) generated by exhaust pressure.
It is characterized in that the force for displacing 9) is offset.

Accordingly, the displacement members (108, 109)
Outflow passage (105) because the force to displace
Even when the exhaust gas flows backward in the inside, it is possible to prevent the on-off valve from opening. For this reason, like the above-mentioned conventional on-off valve, the force in the valve closing direction is always applied to the valve section (10
8a), the force acting on the displacement members (108, 109) is substantially zero except for the elastic force of the elastic means (115).

That is, the elastic means (115) only needs to apply an elastic force to the displacement members (108, 109) to such an extent that the valve does not open due to vehicle vibration or the like. The set load can be made smaller than that of the conventional on-off valve. Therefore, the force required to open the valve can be reduced as compared with the above-described conventional on-off valve, and the valve can be quickly opened.

As described above, according to the present invention, the structure of the on-off valve can be simplified while preventing the valve from opening due to pressure fluctuation, so that the on-off valve can be downsized. The manufacturing cost of the on-off valve can be reduced. According to the second and third aspects of the present invention, the displacement member (108,
109) is disposed on the outflow passage (105) side. And
The displacement members (108, 109) are provided with a first pressure receiving portion (108b) that receives a pressure in a direction to close the valve port (103) and a second pressure receiving portion (109a) that receives a pressure in a direction to open the valve port (103). And the displacement member (108,
109) on both surfaces perpendicular to the direction of displacement.
109a) is characterized in that the projected areas are equal to each other.

Accordingly, the displacement members (108, 109)
Pressure receiving portions (108b, 109b)
Since the areas when a) are projected are equal to each other, the force for displacing the displacement members (108, 109) generated by the exhaust pressure is canceled. Therefore, even if the exhaust gas flows backward in the outflow passage (105), it is possible to prevent the on-off valve from opening.

For this reason, unlike the above-mentioned conventional on-off valve, it is not necessary to always apply a force for closing the valve to the valve portion (108a), and if the elastic force of the elastic means (115) is removed, the displacement member (108) , 109) are substantially zero. As described above, also in the present invention, the same effects as those of the first aspect can be obtained.

According to the third aspect of the present invention, the second pressure receiving portion (109a) is formed of a flat thin film diaphragm (109) which is connected in contact with the first pressure receiving portion (108b). It is characterized by the following. The first pressure receiving section (108
b) and the diaphragm (109) are connected so as to be in contact with each other.
The mass of the displacement member can be made smaller than that in which the diaphragm is connected by the valve rod 34.

Therefore, the set load of the elastic means (115) can be made smaller than that of the conventional on-off valve, and the valve can be opened more quickly. As a result, the structure of the on-off valve can be further simplified. Further, since the second pressure receiving portion (109a) is formed of a flat thin film diaphragm (109), the diaphragm (109), that is, the second pressure receiving portion (109a) is formed.
When the is displaced, it is possible to prevent stress from being partially concentrated. Therefore, the diaphragm (109) can be prevented from being damaged, and the durability of the diaphragm (109) can be improved.

According to a fourth aspect of the present invention, the atmospheric pressure is guided to the back side of the second pressure receiving portion (109a). Thus, unlike the above-described conventional on-off valve, a passage means for guiding the discharge pressure of the air pump to the first diaphragm 30 is not required to open the on-off valve, so that the structure of the on-off valve is further simplified. Can be.

The reference numerals in parentheses of the above means indicate the correspondence with the specific means described in the embodiment described later.

[0016]

FIG. 1 is a schematic diagram of a secondary air supply system using an on-off valve 100 according to the present embodiment.
In FIG. 1, reference numeral 200 denotes an engine, and 201 denotes an engine 2.
Reference numeral 202 denotes an intake pipe (surge tank), and reference numeral 202 denotes an exhaust pipe (exhaust manifold) of the engine 200. On the downstream side of the exhaust pipe 202, an electrically heated catalyst including a catalyst (three-way catalyst) 203 for purifying the exhaust gas by accelerating the oxidation-reduction reaction of the exhaust gas and an electric heater 204 for heating the catalyst 203 Are arranged.

Reference numeral 300 denotes an air pump which operates by receiving electric power from the vehicle battery 301. The air pump 300 supplies air to the on-off valve 100. The operation state of the air pump 300 is controlled by an electronic control unit (ECU) 401 via an air pump control relay 400. Next, the on-off valve 100 will be described with reference to FIG.

Reference numeral 101 denotes an inflow port connected to the discharge side of the air pump 300 and into which air flows, and 102 denotes an exhaust pipe 2.
02 is an outlet connected to the side 02, and 103 is an outlet 1
The valve port connects the inflow passage 104 on the 01 side and the outflow passage 105 on the outflow port 102 side. And valve opening 10
3. Inlet 101, inflow passage 104 and outflow passage 10
5 is formed in the first housing 106 and the outlet 1
02 and a part of the outflow passage 105 are connected to the second housing 10.
7 is formed. The two housings 106, 10
7 are both made of aluminum die-cast.

A lower plate (plate member) 108 having a rubber valve portion 108a for opening and closing the valve port 103 and a first pressure receiving portion 108b described later is disposed in the outflow passage 105. The plate 108 is disposed via a thin-film diaphragm 109 so as to be displaceable in a direction perpendicular to the opening surface of the valve port 103. Incidentally, the lower plate 108 is made of stainless steel, and the diaphragm 109 is made of rubber (in the present embodiment, fluorosilicone or hydrin rubber).

The diaphragm 109 is locked and fixed to an intermediate plate 110 made of aluminum. The intermediate plate 110 is fixed to the first housing 106 by caulking a cover 111 made of a rolled steel plate to the first housing 106. It is fixed to. By the way, a check valve 112 of a thin plate spring for preventing exhaust gas from flowing back toward the valve port 103 is provided on the outflow passage 105 on the outflow port 102 side from the lower plate 108. Depending on the frequency of the pressure fluctuation, the flow rate of the exhaust gas, etc., the check valve 112 does not operate normally, and the exhaust gas is
It may flow backward toward. Incidentally, 112a is a stopper for regulating the maximum opening of the check valve 112.

Therefore, in the present embodiment, the lower plate 1
08 and the diaphragm 109 are connected by rivets 113 in a state where they are in contact with each other.
109 together is called a displacement member. ). The lower plate 108 is provided with a first pressure receiving portion 108 b for receiving a pressure in a direction to close the valve port 103, while the diaphragm 109 has a first pressure receiving portion 108 b.
Pressure receiving portion 10 which receives pressure in the direction of opening valve port 103
9a is provided, and the area when the pressure receiving portions 108b and 109a are projected onto a plane perpendicular to the displacement direction of the displacement member (hereinafter, this area is referred to as a projected area) is configured to be equal to each other. (See FIG. 3).

On the back side of the second pressure receiving portion 109a,
A back chamber 114 to which atmospheric pressure is guided by the diaphragm 109 and the cover 111 is formed. In the back chamber 114, a lower plate 108 is interposed via the diaphragm 109.
A coil spring (elastic means) 115 for applying an elastic force to the (valve portion 108a) in a direction to close the valve port 103 is provided.

Incidentally, reference numeral 111a denotes a breathing hole for guiding atmospheric pressure to the back chamber 114, and 115a constitutes a spring seat of the coil spring 115, and stress concentrates on a portion of the diaphragm 109 connected by the rivet 113. , An upper plate for preventing the diaphragm 109 from being damaged. Also, the second pressure receiving portion 109a
In the present embodiment, the second pressure receiving portion 109a has a flat shape without any irregularities because the second pressure receiving portion 109a is exposed to the exhaust gas and directly receives the exhaust pressure fluctuation.

Next, the characteristic operation and characteristics of the on-off valve 100 will be described. As described above, when the check valve 112 does not operate normally and the exhaust gas flows backward, the first pressure receiving portion 10
8b and the second pressure receiving portion 109a, the two pressure receiving portions 108b and 1b are arranged so that the projected areas are equal to each other.
As a result, the force for displacing the displacement member generated by the exhaust pressure (hereinafter, this force is referred to as the displacement force) is canceled out (see FIG. 3). Therefore, even when the exhaust gas flows backward in the outflow passage 105, it is possible to prevent the on-off valve 100 from opening.

The exhaust pressure may be increased (positive pressure) or decreased (negative pressure). In either case, the first pressure receiving portion 108b is operated by the valve portion 108b. 108
a (lower plate 108), and the direction of the force applied to the second pressure receiving portion 109a corresponds to the valve portion 108a (lower plate 10).
Since the direction of the force applied to 8) is opposite, the displacement force can be surely canceled even if any of positive pressure and negative pressure acts in the outflow passage 105.

The valve section 108a (lower plate 10)
Since 8) is disposed on the outflow passage 105 side, the exhaust pressure acts on the valve portion 108a (lower plate 108) in a direction to close the valve. For this reason, unlike the above-described conventional on-off valve, it is not necessary to always apply a force in the valve closing direction to the valve portion 108a (lower plate 108). Therefore, except for the elastic force of the coil spring 115, the force acting on the displacement member is not required. Is substantially zero.

That is, the coil spring 115 applies an elastic force to the displacement member (lower plate 108) to such an extent that the displacement member (lower plate 108) does not vibrate due to vehicle vibration or the like and the valve port 103 is opened. Since it only needs to be applied, the set load of the coil spring 115 can be reduced as compared with the conventional on-off valve. Therefore, in the present embodiment, the force required to open the valve port 103 can be reduced as compared with the conventional on-off valve. In the end,
Since the structure of the on-off valve 100 can be simplified,
The size of the on-off valve 100 can be reduced, and the manufacturing cost of the on-off valve 100 can be reduced.

Further, since the lower plate 108 and the diaphragm 109 are connected in contact with each other, the first and second diaphragms are connected to the valve rod 34 as in the above-mentioned conventional on-off valve.
Thus, the mass of the displacement member can be reduced as compared with the one connected by. Therefore, the set load of the coil spring 115 can be made smaller than that of the above-described conventional on-off valve, so that the valve port 103 can be opened more quickly. As a result, the structure of the on-off valve 100 can be further simplified.

Further, the second pressure receiving portion 1 of the diaphragm 109
Since 09a has a flat shape without irregularities, it is possible to prevent stress from being partially concentrated when the diaphragm 109 is displaced. Therefore, the diaphragm 109
Can be prevented from being damaged.
Can be improved in durability. By the way, the overall shape of the diaphragm 109 is not limited to the dish shape shown in FIG. 2, but as shown in FIG.
Not only a but also the entire diaphragm 109 may be flat.

In the above embodiment, the displacement member is constituted by the lower plate 108 and the diaphragm 109. However, the present invention is not limited to this. For example, like a spool valve element of a spool type on-off valve, A circumferential groove may be provided in the cylindrical spool valve body, and the side surfaces of the groove may be the first and second pressure receiving portions 108b and 109a. In addition,
In this case, the displacement direction of the displacement member coincides with the longitudinal direction of the spool valve body.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a secondary air supply system.

FIG. 2 is a cross-sectional view of the on-off valve according to the embodiment of the present invention.

FIG. 3 is an enlarged view of first and second pressure receiving portions.

FIG. 4 is a sectional view of an on-off valve according to a modification of the present invention.

FIG. 5 is a sectional view of an on-off valve according to the related art.

[Explanation of symbols]

101 ... inlet, 102 ... outlet, 103 ... valve, 10
4. Inflow passage, 105 outflow passage, 106 first housing, 107 second housing, 108 lower plate, 108a valve section, 108b first pressure receiving section, 109
Diaphragm, 109a ... second pressure receiving portion.

Claims (4)

[Claims] 1. A secondary air passage opening / closing valve provided in a secondary air passage for guiding air to an exhaust pipe (202) of an internal combustion engine, and for opening and closing the secondary air passage, wherein an inlet through which air flows in (101) and the exhaust pipe (2)
02), and a valve port (103) for communicating an inflow passage (104) on the inflow port (101) side with an outflow passage (105) on the outflow port (102) side. A displacement member (108, 109) that is displaceably disposed on the outflow passage (105) side and has a valve portion (108a) that opens and closes the valve port (103). Elastic means (115) for applying an elastic force in a direction to close the valve port (103) to the valve portion (108a); and the displacement member (108, 109) includes the valve port (10).
3) The first pressure receiving portion (108) receiving the pressure in the direction of closing
b) and a second pressure receiving portion (109a) that receives a pressure in a direction to open the valve port (103). Further, the two pressure receiving portions (108b, 109a) are further provided with the two pressure receiving portions (108b, 109. A secondary air passage opening / closing valve configured to cancel a force for displacing the displacement member (108, 109) due to a pressure received by 109a). 2. A secondary air passage opening / closing valve which is provided in a secondary air passage for guiding air to an exhaust pipe (202) of an internal combustion engine, and opens and closes the secondary air passage, wherein an inflow port through which air flows in (101) and the exhaust pipe (2)
02), and a valve port (103) for communicating an inflow passage (104) on the inflow port (101) side with an outflow passage (105) on the outflow port (102) side. A displacement member (108, 109) that is displaceably disposed on the outflow passage (105) side and has a valve portion (108a) that opens and closes the valve port (103). Elastic means (115) for applying an elastic force in a direction to close the valve port (103) to the valve portion (108a); and the displacement member (108, 109) includes the valve port (10).
3) The first pressure receiving portion (108) receiving the pressure in the direction of closing
b) and a second pressure receiving portion (109a) for receiving a pressure in a direction to open the valve port (103). A secondary air passage opening / closing valve characterized in that the pressure receiving parts (108b, 109a) are configured so that their areas when projected are equal to each other. 3. The second pressure receiving portion (109a) is formed of a flat thin-film diaphragm (109) connected to and connected to the first pressure receiving portion (108b). The secondary air passage opening / closing valve according to claim 1. 4. The valve receiving portion (108a) of the displacement member (108, 109) includes a first pressure receiving portion (108b).
The second pressure receiving portion (109a) is formed on the first pressure receiving portion (108).
4. The pressure receiving device according to claim 1, wherein the pressure receiving portion is formed so as to face the second pressure receiving portion.
The secondary air passage opening / closing valve according to any one of the above.